Sample collection
We collected samples in two villages in the Cross-Cutucu region of Morona Santiago, ´
Ecuador. Village 1 (V1; pop. 50) is located approximately one to four hours by motorized
canoe (depending on water levels) from the nearest port with road access. A nearby spring
located upstream from the village provides water for bathing and cooking. Village 2 (V2;
pop. 400) is located twenty-minutes by foot from V1 (including a bridgeless river crossing).
Water is pumped from the river to a reserve that flows through pipes to some houses. In
both villages, each household has their own chicha ferment, containing brews that are
commonly maintained by the resident women. New batches are produced every 3–5 days
or as needed.
We collected 2 mL of mature chicha from five households in V1 and two households
in V2, during August 2012 (sample volume was limited due to limited freezer space on
site). Over a period of two weeks, we collected samples from each of these seven ferments
up to three times, each representing independent batches (with a shared starter culture).
Fermentation maturity of samples was confirmed with litmus paper ensuring a pH range
between 4.0 and 4.5 (Luedeking & Piret, 1959; Santos et al., 2012). We sampled 300 mL
of spring water (concentrated on a 0.45 µm pore, cellulose acetate filter) that residents
in V1 use to prepare chicha. We were unable to collect water from V2 due to equipment
malfunction. All samples were immediately frozen (−20 ◦C) before being transported and
stored at the University of Oregon until they were processed. All samples were examined
under a light microscope for evidence of helminth eggs or macrophages.